Multiplexer

ABSTRACT

Embodiments of the present disclosure provide a multiplexer, and relate to the field of fiber communications technologies. The multiplexer according to the embodiments of the present disclosure includes a first light beam adjusting element, a second light beam adjusting element, a first light filtering and combining element or splitting element, a second light filtering and combining element or splitting element, a polarization changing element, and a light polarizing and combining element. The optical multiplexer according to the embodiments of the present disclosure may not only implement combining at least four light beams into one light beam but also reduce the number of reflection times of light during a light combination process.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. patentapplication Ser. No. 14/977,539 filed on Dec. 21, 2015, which claimspriority to Chinese Patent Application No. 201510086181.9 filed on Feb.16, 2015, the disclosures of which are incorporated herein in itsentirety by reference.

TECHNICAL FIELD

The present disclosure relates to the optical communications field, andin particular, to a multiplexer.

BACKGROUND

Currently, a wavelength division multiplexing technology, especially adense wavelength division multiplexing technology has become one of maintechnologies used to implement high-speed and large-capacity datatransmission in the optical communications field. In order to implementwavelength division multiplexing, a multiplexer is required to combinemultiple light beams of different wavelengths into one light beam.

FIG. 1 is a multiplexer provided in the conventional art. As shown inFIG. 1, an existing multiplexer includes a rhombic prism. One side ofthe rhombic prism is coated with an anti-reflection film and a highreflection film, and four thin-film filters are attached to another sideof the rhombic prism. The anti-reflection film improves lighttransmission, and the high reflection film improves light reflection.Filter characteristics of the thin-film filter make a light beam of aspecified wavelength be transmitted and a light beam of a non-specifiedwavelength be reflected. The four thin-film filters have differentfilter characteristics from each other.

An incident light beam λ1, an incident light beam λ2, an incident lightbeam λ3, and an incident light beam λ4 are four light beams of specifiedwavelengths to be combined. The incident light beam λ1 enters therhombic prism from a thin-film filter T1, and is reflected to anotherthin-film filter T2 at the high reflection film, and then reflected tothe high reflection film by the another thin-film filter T2; theincident light beam λ2 enters the rhombic prism from the thin-filmfilter T2; and the incident light beam λ1 and λ2 are combined into onelight beam at the thin-film filter T2.

The combined incident light beam λ1 and λ2 enter the high reflectionfilm, and is reflected to another thin-film filter T3 at the highreflection film, and then is reflected to the high reflection film bythe another thin-film filter T3; the incident light beam λ3 enters therhombic prism from the thin-film filter T3; and the incident light beamλ1, λ2, and λ3 are combined into one light beam at the thin-film filterT3.

The combined incident light beam λ1, λ2, and λ3 enter the highreflection film, and is reflected to another thin-film filter T3 at thehigh reflection film, and then is reflected to the high reflection filmby the another thin-film filter T3; the incident light beam λ4 entersthe rhombic prism from a thin-film filter T4; the incident light beamλ1, λ2, λ3, and λ4 are combined into one light beam at the thin-filmfilter T4, and the combined incident light beam λ1, λ2, λ3, and λ4enters the anti-reflection film and emerges from the anti-reflectionfilm.

In the foregoing conventional art, although the combining four lightbeams of different wavelengths into one light beam is implemented, themultiplexer has six optical reflection points, the incident light beamA1 is reflected six times, the incident light beam λ2 is reflected fourtimes, and the incident light beam λ3 is reflected two times, and thusthe four light beams are reflected twelve times totally. The light isreflected for many times in the multiplexer. The light is reflected formany times in the multiplexer, so during a reflection process, theincident light beams λ1, λ2, λ3, and λ4 are combined into one beam insequence, and the four incident light beams are overlapped inside themultiplexer in sequence, which makes that, during a process ofimplementing light beam combination, an incident position and anincident angle of each incident light beam, and precision of themultiplexer are highly required, and thereby causing difficulties inmanufacturing.

SUMMARY

The embodiments of the present disclosure provide a multiplexer, whichmay not only implement combining at least four light beams into onelight beam but also reduce reflection times of light during a lightcombination process.

To achieve the foregoing objective of the disclosure, the embodiments ofthe present disclosure adopts the following technical solutions:

A multiplexer according to an embodiment of the present disclosure isconfigured to combine at least four light beams of different wavelengthsemitted from a laser into one light beam, including:

a first light beam adjusting element, where the first light beamadjusting element is configured to adjust propagation directions of afirst light beam and a second light beam;

a first light filtering and combing element, where the first lightfiltering and combing element is configured to combine a third lightbeam and the first light beam adjusted by the first light beam adjustingelement into a fifth light beam;

a second light filtering and combing element, where the second lightfiltering and combing element is configured to combine a fourth lightbeam and the second light beam adjusted by the first light beamadjusting element into a sixth light beam;

a polarization state changing element, where the polarization statechanging element is configured to change a polarization state of thesixth light beam to output a seventh light beam a second light beamadjusting element, where the second light beam adjusting element isconfigured to adjust a propagation direction of the fifth light beam orthe seventh light beam; and

a light polarizing and combing element, where the light polarizing andcombing element is configured to combine, after the propagationdirection of the fifth light beam or the seventh light beam is adjustedby the second light beam adjusting element, the fifth light beam and theseventh light beam into one light beam.

The multiplexer according to the embodiments of the present disclosureis configured to combine at least four light beams of differentwavelengths emitted from the laser into one light beam, where the firstlight filtering and combing element is configured to combine the thirdlight beam and the first light beam adjusted by the first light beamadjusting element to the fifth light beam; the second light filteringand combing element is configured to combine the fourth light beam andthe second light beam adjusted by the first light beam adjusting elementto the sixth light beam; the polarization state changing element isconfigured to change the polarization state of the sixth light beam tooutput the seventh light beam; and the light polarizing and combingelement is configured to combine, after the propagation direction of thefifth light beam or the seventh light beam is adjusted by the secondlight beam adjusting element, the fifth light beam and the seventh lightbeam into one light beam. Therefore, the combing at least four lightbeams into one light beam is implemented.

During a process of combining at least four light beams into one lightbeam, a light beam is reflected at most four times at the first lightbeam adjusting element, the first light filtering and combing element orthe second light filtering and combing element, the second light beamadjusting element, and the light polarizing and combing elementrespectively; and a light beam is reflected at least zero time. When thecombing at least four light beams into one light beam is implemented,the four light beams are reflected at most eight times, and comparedwith the conventional art, not only the maximum number of reflectiontimes of a light beam is reduced but also the total number of reflectiontimes of the light beams is reduced, and therefore, the number ofreflection times of light during the light combination process isreduced.

BRIEF DESCRIPTION OF THE DRAWINGS

To illustrate the technical solutions in the embodiments of the presentdisclosure more clearly, the following briefly introduces theaccompanying drawings required for describing the embodiments or theconventional art. Apparently, the accompanying drawings in the followingdescription show merely some embodiments of the present disclosure, anda person of ordinary skill in the art may still derive other drawingsfrom these accompanying drawings without creative efforts.

FIG. 1 is a schematic diagram of a structure principle of a multiplexerin the conventional art;

FIG. 2 is a schematic structural diagram of a multiplexer according toan embodiment of the present disclosure;

FIG. 3 is a schematic structural diagram of another multiplexeraccording to an embodiment of the present disclosure;

FIG. 4 is a schematic structural diagram of another multiplexeraccording to an embodiment of the present disclosure;

FIG. 5 is a schematic structural diagram of another multiplexeraccording to an embodiment of the present disclosure;

FIG. 6 is a schematic structural diagram of another multiplexeraccording to an embodiment of the present disclosure;

FIG. 7 is a schematic structural diagram of another multiplexeraccording to an embodiment of the present disclosure;

FIG. 8 is a schematic structural diagram of another multiplexeraccording to an embodiment of the present disclosure;

FIG. 9 is a schematic structural diagram of another multiplexeraccording to an embodiment of the present disclosure;

FIG. 10 is a schematic structural diagram of another multiplexeraccording to an embodiment of the present disclosure; and

FIG. 11 is a schematic structural diagram of another multiplexeraccording to an embodiment of the present disclosure. For FIGS. 1-11, afirst light beam λ1, a second light beam λ2, a third light beam λ3, afourth light beam λ4, a first light beam adjusting element 201, a laseremitter λ1, a laser emitter A2, a laser emitter A3, a laser emitter A4,a fiber B1, a first light filtering and combing element 202, a secondlight filtering and combining element 203, a polarization state changingelement 204, a second light beam adjusting element 205, a lightpolarizing and combing element 206, a first subelement 401, a secondsubelement 402, a third light beam adjusting element 403, a firstilluminator 300, a second illuminator 400, an anti-reflection element301, a collimation element 302, a first illuminator 501, a secondilluminator 502, and a third illuminator 503.

FIGS. 12-21 are schematic structural diagram of multiplexers accordingto other embodiments of the present disclosures. The light filtering andcombining element 202 and/or 203 are replaced with a light slittingelement.

DETAILED DESCRIPTION

The following clearly and completely describes the technical solutionsin the embodiments of the present disclosure with reference to theaccompanying drawings in the embodiments of the present disclosure.Apparently, the described embodiments are some of the embodiments of thepresent disclosure rather than all of the embodiments. All otherembodiments obtained by persons of ordinary skill in the art based onthe embodiments of the present disclosure without creative efforts shallfall within the protection scope of the present disclosure.

Currently, a wavelength division multiplexing technology, especially adense wavelength division multiplexing technology has become one of maintechnologies used to implement high-speed and large-capacity datatransmission in the optical communications field. In order to implementwavelength division multiplexing, a multiplexer is required to combinemultiple light beams of different wavelengths into one light beam. Themultiple beams, for example, may be coupled into a single optical fiber.

Examples of wavelengths and polarization states in the presentdisclosure do not constitute limitations to the technical solutionsprotected by the present disclosure. According to the technicalsolutions provided in the disclosure of the present disclosure, a personskilled in the art may set a wavelength of a light beam and apolarization state of a light beam according to requirements.

FIG. 2 is a schematic structural diagram of a multiplexer according toan embodiment of the present disclosure. As shown in FIG. 2, amultiplexer according to the embodiment of the present disclosure isconfigured to combine at least four light beams of different wavelengthsemitted from a laser into one light beam.

For example, a laser emitter A1 emits a first light beam λ1 ofwavelength λ1, a laser emitter A2 emits a second light beam λ2 ofwavelength λ2, a laser emitter A3 emits a third light beam λ3 ofwavelength λ3, a laser emitter A4 emits a fourth light beam λ4 ofwavelength λ4, and by using a multiplexing function of the multiplexer,the finally output combined light beam λ1, λ2, λ3, and λ4 enters a fiberB1.

The multiplexer according to the embodiment of the present disclosureincludes a first light beam adjusting element 201, a second light beamadjusting element 205, a first light filtering and combing element 202,a second light filtering and combining element 203, a polarization statechanging element 204, and a light polarizing and combining element 206.

The multiplexer according to the embodiment of the present disclosuremay combine at least four light beams of different wavelengths into onelight beam. Because the light emitted from the laser is polarized light,the first light beam λ1, the second light beam λ2, the third light beamλ3, and the fourth light beam λ4 represent four polarized light beams ofdifferent wavelengths.

The sequence of the first light beam λ1, the second light beam λ2, thethird light beam λ3, and the fourth light beam λ4 is not fixed. Thepresent disclosure uses the sequence shown in FIG. 1 as an example toillustrate the technical solutions provided in the present disclosure.

The first light beam adjusting element 201 is configured to adjustpropagation directions of the first light beam A1 and the second lightbeam λ2, so that the first light beam λ1 is input to the first lightfiltering and combing element 202, and the second light beam λ2 is inputto the second light filtering and combing element 203.

The light beam adjusting element is preferred to be a total reflectionfilm, or may also be a reflection film or a prism, which is not limitedin the present disclosure. The light beam adjusting element may be anyelement that may implement adjusting the light propagation direction.The light propagation direction may be adjusted by using totalreflection of light or reflection of light, or may also be adjusted byusing refraction of light.

To reduce loss of light energy, a high reflection film may be coated onthe light beam adjusting element 201.

The first light filtering and combing element 202 is configured tocombine the third light beam λ3 and the first light beam λ1 adjusted bythe first light beam adjusting element 201 to a fifth light beam λ1 λ3.

The second light filtering and combining element 203 combines the fourthlight beam λ4 and the second light beam λ2 adjusted by the first lightbeam adjusting element into a sixth light beam λ2λ4.

The light filtering and combining element reflects light beams of somewavelengths and transmits light beams of other wavelengths according todifferent wavelengths of light beams. Any component satisfying theforegoing characteristics may be the light filtering and combingelement.

In the present disclosure, the light filtering and combing elementreceives two light beams of different wavelengths, where one light beamis reflected by the light filtering and combining element and anotherlight beam is transmitted by the light filtering and combing element.

For example, the first light beam λ1 and the third light beam λ3 arelight beams of different wavelengths, and the second light beam λ2 andthe fourth light beam λ4 are light beams of different wavelengths. Thefirst light filtering and combing element 202 reflects the first lightbeam A1 and transmits the third light beam λ3, and the second lightfiltering and combing element 203 reflects the second light beam λ2 andtransmits the fourth light beam λ4.

At the first light filtering and combing element 202, the first lightbeam λ1 may be reflected by the first light filtering and combingelement 202, the third light beam λ3 may be transmitted by the firstlight filtering and combing element 202, and the reflected first lightbeam λ1 and the transmitted third light beam λ3 have the same lightpath, so that combining the first light beam λ1 and the third light beamλ3 into one light beam is implemented; or the first light beam λ1 may betransmitted by the first light filtering and combing element 202, thethird light beam λ3 may be reflected by the first light filtering andcombining element 202, and the transmitted first light beam λ1 and thereflected third light beam λ3 have the same light path, so thatcombining the first light beam λ1 and the third light beam λ3 into onelight beam is implemented.

At the second light filtering and combing element 203, the second lightbeam λ2 may be reflected by the second light filtering and combingelement 203, the fourth light beam λ4 may be transmitted by the secondlight filtering and combing element 203, and the reflected second lightbeam λ2 and the transmitted fourth light beam λ4 have the same lightpath, so that combining the second light beam λ2 and the fourth lightbeam λ4 into one light beam is implemented; or the second light beam λ2may be transmitted by the second light filtering and combing element203, the fourth light beam λ4 is reflected by the second light filteringand combining element 203, and the transmitted second light beam λ2 andthe reflected fourth light beam λ4 have the same light path, so thatcombining the second light beam λ2 and the fourth light beam λ4 into onelight beam is implemented.

In the present disclosure, after entering the first light filtering andcombining element 202 at an appropriate angle, the third light beam λ3and the first light beam λ1 entering the first light filtering andcombining element 202 are just combined into one light beam; and afterentering the second light filtering and combining element 203 at anappropriate angle, the fourth light beam λ4 and the second light beam λ2entering the second light filtering and combining element 203 are justcombined into one light beam.

The at least four light beams need to be combined by the multiplexer arelight beams of different wavelengths, and two light beams combined bythe light filtering and combining element meet wavelength requirementsof the light filtering and combining element for reflecting andtransmitting light.

The first light beam adjusting element 201 is configured to adjust thepropagation directions of the first light beam λ1 and the second lightbeam λ2, so that the first light beam A1 is input to the first lightfiltering and combing element 202, and the second light beam λ2 is inputto the second light filtering and combing element 203; the third lightbeam λ3 may be input to the first light filtering and combining element202 directly, or may be input to the first light filtering and combiningelement 202 after the propagation direction of the third light beam λ3is adjusted by another component; and the fourth light beam λ4 may beinput to the second light filtering and combining element 203 directly,or may be input to the second light filtering and combining element 203after the propagation direction of the fourth light beam λ4 is adjustedby another component.

The light filtering and combining element may be a thin-film filter.According to the difference between wavelengths of reflection light andtransmission light, the thin-film filter may be a high-transmission andlow-reflection thin-film filter, or may be a low-transmission andhigh-reflection thin-film filter.

The polarization state changing element 204 is configured to change apolarization state of the sixth light beam λ2λ4 to output a seventhlight beam. After the polarization state of the sixth light beam λ2λ4 ischanged, the seventh light beam λ′2λ′4 is obtained.

The polarization state changing element 204 may be a granting, a waveplate, or a half-wave plate. Any component that may change the lightpolarization direction may be a polarization state changing element 204.

Two light beams combined by the light polarizing and combining element206 meets polarization state requirements of the light polarizing andcombining element 206 for reflecting and transmitting light.

The second light beam adjusting element 205 is configured to adjust apropagation direction of the fifth light beam λ1 λ3 or the seventh lightbeam λ′2λ′4, so that the fifth light beam λ1 λ3 or the seventh lightbeam λ′2λ′4 is input to the light polarizing and combining element 206.

Polarization states of some light beams of multiple light beams formedafter light combination performed by the light filtering and combiningelement are changed by the polarization state changing element 204, sothat multiple types of light in different polarization states areformed. Each type of light includes at least one light beam. Forexample, a polarization state of the fifth light beam λ1 λ3 and apolarization state of the seventh light beam λ′2λ′4 are perpendicular toeach other.

The second light beam adjusting element 205 is configured to change apropagation direction of any one type of light of the multiple types oflight in different polarization states. For example, the second lightbeam adjusting element 205 is configured to adjust the propagationdirection of the seventh light beam λ′2A λ4, so that the seventh lightbeam λ′2λ′4 is input to the light polarizing and combining element 206.

The first light beam adjusting element 201 and the second light beamadjusting element 205 may use specific same components, or may usespecific different components. In a specific implementation process, ifnames of specific components are the same, the specific componentsshould not be considered the same.

The light polarizing and combining element 206 is configured to combinethe fifth light beam and the seventh light beam into one light beam λ1λ2A λ3 λ4.

In the embodiment of the present disclosure, the light polarizing andcombining element 206 is disposed on a light path of the fifth lightbeam λ1 λ3 output by the first light filtering and combining element202, while the second light beam adjusting element 205 is disposed on alight path of the seventh light beam λ′2λ′4 output by the polarizationstate changing element 204 to change the propagation direction of theseventh light beam to make the seventh light beam input to the lightpolarizing and combining element 206.

The light polarizing and combining element 206 may reflect light of somepolarization directions and transmit light of other polarizationdirections according to different light polarization directions. Anyspecific component satisfying the foregoing characteristics may be thelight polarizing and combining element 206. The light polarizing andcombining element 206 may be a polarization beam combiner (PBC).

Light beams of different wavelengths enter the light filtering andcombining element from two sides of the light filtering and combiningelement respectively, and the light filtering and combining elementtransmits light beams of some wavelengths and reflects light beams ofother wavelengths, so that the light beams transmitted or reflected bythe light filtering and combining element are located at one side of thelight filtering and combining element. By controlling angles of lightbeams of different wavelengths entering the light filtering andcombining element, the light beams transmitted or reflected by the lightfiltering and combining element may be combined into one light beam atone side of the light filtering and combining element.

Two light beams of different wavelengths may be combined into one lightbeam by using the foregoing design. Four light beams of differentwavelengths may be combined into two light beams by reusing theforegoing design.

The light emitted from the laser is polarized light, and the foregoinglight combination according to wavelengths does not change thepolarization state of each light beam, so the foregoing two light beamsstill remain their original polarization states. One light beam of thetwo light beams is adjusted by using the polarization state changingelement 204, so that the polarization states of the two light beams aredifferent.

The light beams in different polarization states enter the lightpolarizing and combining element 206 from two sides of the lightpolarizing and combining element 206, and the light polarizing andcombining element 206 transmits light beams in a polarization state andreflects light beams in other polarization states, so that the lightbeams transmitted or reflected by the light polarizing and combiningelement 206 are located at one side of the light polarizing andcombining element 206. By controlling angles of light beams in differentpolarization states entering the light polarizing and combining element206, the light beams transmitted or reflected by the light polarizingand combining element 206 may be combined into one light beam at oneside of the light polarizing and combining element 206.

Two light beams in different polarization states may be combined intoone light beam by using the foregoing design.

The first light beam adjusting element 201 make light beams of differentwavelengths locate at two sides of the light filtering and combiningelement by changing the propagation direction of the light beam; and thesecond light beam adjusting element 205 make light beams in differentpolarization states locate at two side of the light polarizing andcombining element 206 by changing the propagation direction of the lightbeam.

The four light beams of different wavelengths emitted from the laser arecombined into one light beam through an interaction among the firstlight beam adjusting element 201, the first light filtering andcombining element 202, the second light filtering and combining element203, the polarization state changing element 204, the second light beamadjusting element 205, and the light polarizing and combining element206.

To reduce loss of light energy, a high reflection film is coated on thesecond light beam adjusting element 205, so as to strengthen lightreflection.

Because the sequence of the first light beam, the second light beam, thethird light beam, and the fourth light beam is not fixed, any one lightbeam of multiple light beams formed after the light combinationperformed by multiple light filtering and combining elements may be thesixth light beam, and any one of other light beams may be the fifthlight beam. The light beam sequence shown in the accompany drawings ofthe present disclosure cannot be understood as limitations to thetechnical solutions of the present disclosure.

During a process of combining at least four light beams into one lightbeam, the second light beam is reflected most times. The second lightbeam is reflected four times at the first light beam adjusting element201, the second light filtering and combing element 203, the secondlight beam adjusting element 205, and the light polarizing and combingelement 206 respectively; and the third light beam is reflected zerotime. When the combing four light beams into one light beam isimplemented, the four light beams are reflected at most eight times, andcompared with the conventional art, not only the maximum number ofreflection times of a light beam is reduced but also the total number ofreflection times of the light beams are reduced, and therefore, thenumber of reflection times of the light beams during the lightcombination process is reduced.

FIG. 3 is a schematic structural diagram of another multiplexeraccording to an embodiment of the present disclosure. As shown in FIG.3, the sequence of incident lights of the multiplexer according to theembodiment of the present disclosure is different from that in FIG. 2.According to the technical solutions provided in the present disclosure,a person skilled in the art may set an appropriate light beam sequenceaccording to requirements. Specific light beam sequences provided in theaccompany drawings of the present disclosure cannot be understood aslimitations to the protection scope of the present disclosure.

FIG. 4 is a schematic structural diagram of another multiplexeraccording to an embodiment of the present disclosure. As shown in FIG.4, the multiplexer according to the embodiment of the present disclosureincludes a first light beam adjusting element 201, a second light beamadjusting element 205, a first light filtering and combing element 202,a second light filtering and combining element 203, a polarization statechanging element 204, and a light polarizing and combining element 206.

For example, the second light beam adjusting element 205 is configuredto adjust a propagation direction of a fifth light beam λ1 λ3, so thatthe fifth light beam λ1 λ3 is input to the light polarizing andcombining element 206.

The polarization state changing element 204 changes polarization statesof a second light beam λ2 and a fourth light beam M to obtain a seventhlight beam λ2λ′4.

The light polarizing and combining element 206 is disposed on a lightpath of the seventh light beam λ2λ′4 output by the polarization statechanging element 204, while the second light beam adjusting element 205is disposed on a light path of the fifth light beam λ1 λ3 output by thefirst light filtering and combining element 202 to change thepropagation direction of the fifth light beam to make the fifth lightbeam input to the light polarizing and combining element 206.

FIG. 5 is a schematic structural diagram of another multiplexeraccording to an embodiment of the present disclosure. As shown in FIG.5, the multiplexer according to the embodiment of the present disclosureincludes a first light beam changing element, a first light filteringand combining element 202, a second light filtering and combiningelement 203, a polarization state changing element 204, a third lightbeam adjusting element 403, and a light polarizing and combining element206, where the first light beam adjusting element includes a firstsubelement 401 and a second subelement 402.

The multiplexer according to the embodiment of the present disclosuremay combine at least four light beams of different wavelengths into onelight beam. Because light emitted from a laser is polarized light, afirst light beam λ1, a second light beam λ2, a third light beam λ3, anda fourth light beam λ4 represent four polarized light beams of differentwavelengths.

The sequence of the first light beam λ1, the second light beam λ2, thethird light beam λ3, and the fourth light beam λ4 is not fixed. Thepresent disclosure uses the sequence shown in FIG. 1 as an example toillustrate the technical solutions provided in the present disclosure.

The first subelement 401 adjusts a propagation direction of the firstlight beam λ1, so that the first light beam λ1 is input to the firstlight filtering and combining element 202; and the second subelement 402adjusts a propagation direction of the second light beam λ2, so that thesecond light beam λ2 is input to the second light filtering andcombining element 203.

The light beam adjusting element is preferred to be a total reflectionfilm, or may also be a reflection film or a prism, which is not limitedin the present disclosure. The light beam adjusting element may be anyelement that may implement adjusting the light propagation direction.The light propagation direction may be adjusted by using totalreflection of light or reflection of light, or may also be adjusted byusing refraction of light.

To reduce loss of light energy, a high reflection film may be coated onthe light beam adjusting element.

The first light filtering and combining element 202 is configured tocombine the first light beam λ1 and the third light beam λ3 into a fifthlight beam λ1 λ3.

The second light filtering and combining element 203 is configured tocombine the second light beam λ2 and the fourth light beam λ4 into asixth light beam λ2λ4.

The light filtering and combining element reflects light beams of somewavelengths and transmits light beams of other wavelengths according todifferent wavelengths of light beams. Any component satisfying theforegoing characteristics may be the light filtering and combingelement.

In the present disclosure, the light filtering and combing elementreceives two light beams of different wavelengths, where one light beamis reflected by the light filtering and combining element and anotherlight beam is transmitted by the light filtering and combing element.

For example, the first light beam λ1 and the third light beam λ3 arelight beams of different wavelengths, and the second light beam λ2 andthe fourth light beam λ4 are light beams of different wavelengths. Thefirst light filtering and combing element 202 reflects the first lightbeam λ1 and transmits the third light beam λ3, and the second lightfiltering and combing element 203 reflects the second light beam λ2 andtransmits the fourth light beam λ4.

At the first light filtering and combing element 202, the first lightbeam λ1 may be reflected by the first light filtering and combingelement 202, the third light beam λ3 may be transmitted by the firstlight filtering and combing element 202, and the reflected first lightbeam λ1 and the transmitted third light beam λ3 have the same lightpath, so that combining the first light beam λ1 and the third light beamλ3 into one light beam is implemented; or the first light beam λ1 may betransmitted by the first light filtering and combing element 202, thethird light beam λ3 may be reflected by the first light filtering andcombining element 202, and the transmitted first light beam λ1 and thereflected third light beam λ3 have the same light path, so thatcombining the first light beam A1 and the third light beam λ3 into onelight beam is implemented.

At the second light filtering and combing element 203, the second lightbeam λ2 may be reflected by the second light filtering and combingelement 203, the fourth light beam λ4 may be transmitted by the secondlight filtering and combing element 203, and the reflected second. lightbeam λ2 and the transmitted fourth light beam λ4 have the same lightpath, so that combining the second light beam λ2 and the fourth lightbeam λ4 into one light beam is implemented; or the second light beam λ2may be transmitted by the second light filtering and combing element203, the fourth light beam λ4 is reflected by the second light filteringand combining element 203, and the transmitted second light beam λ2 andthe reflected fourth light beam λ4 have the same light path, so thatcombining the second light beam λ2 and the fourth light beam λ4 into onelight beam is implemented.

In the present disclosure, after entering the first light filtering andcombining element 202 at an appropriate angle, the third light beam λ3and the first light beam λ1 entering the first light filtering andcombining element 202 are just combined into one light beam; and afterentering the second light filtering and combining element 203 at anappropriate angle, the fourth light beam λ4 and the second light beam λ2entering the second light filtering and combining element 203 are justcombined into one light beam.

The at least four light beams need to be combined by the multiplexer arelight beams of different wavelengths, and two light beams combined bythe light filtering and combining element meet wavelength requirementsof the light filtering and combining element for reflecting andtransmitting light.

The first subelement 401 is configured to adjust the propagationdirection of the first light beam λ1, so that the first light beam λ1 isinput to the first light filtering and combing element 202, and thesecond subelement 402 is configured to adjust the propagation directionof the second light beam λ2, so that the second light beam λ2 is inputto the second light filtering and combing element 203; the third lightbeam λ3 may be input to the first light filtering and combining element202 directly, or may be input to the first light filtering and combiningelement 202 after the propagation direction of the third light beam λ3is adjusted by another component; and the fourth light beam λ4 may beinput to the second light filtering and combining element 203 directly,or may be input to the second light filtering and combining element 203after the propagation direction of the fourth light beam λ4 is adjustedby another component.

The light filtering and combining element may be a thin-film filter.According to the difference between wavelengths of reflection light andtransmission light, the thin-film filter may be a high-transmission andlow-reflection thin-film filter, or may be a low-transmission andhigh-reflection thin-film filter.

The polarization state changing element 204 is configured to change apolarization state of the sixth light beam λ2λ4, and after thepolarization state of the sixth light beam is changed, a seventh lightbeam λ′2λ′4 is obtained.

Because the sequence of the first light beam, the second light beam, thethird light beam, and the fourth light beam is not fixed, any one lightbeam of multiple light beams formed after the light combinationperformed by multiple light filtering and combining elements may be thesixth light beam, and any one of other light beams may be the fifthlight beam. The light beam sequence shown in the accompany drawings ofthe present disclosure cannot be understood as limitations to thetechnical solutions of the present disclosure.

The polarization state changing element 204 may be a granting, a waveplate, or a half-wave plate. Any component that may change the lightpolarization direction may be a polarization state changing element 204.

Two light beams combined by the light polarizing and combining element206 meets polarization state requirements of the light polarizing andcombining element 206 for reflecting and transmitting light.

The third light beam adjusting element 403 is configured to adjust apropagation direction of the fifth light beam λ1 λ3 or the seventh lightbeam λ′2λ′4, so that the fifth light beam λ1 λ3 or the seventh lightbeam λ′2λ′4 is input to the light polarizing and combining element 206.

Polarization states of some light beams of multiple light beams formedafter light combination performed by the light filtering and combiningelement are changed by the polarization state changing element 204, sothat multiple types of light in different polarization states areformed. Each type of light includes at least one light beam. Forexample, a polarization state of the fifth light beam λ1 λ3 and apolarization state of the seventh light beam k*2λ4 are perpendicular toeach other.

The third light beam adjusting element 403 is configured to change apropagation direction of any one type of light of the multiple types oflight in different polarization states. For example, the third lightbeam adjusting element 403 is configured to adjust the propagationdirection of the seventh light beam λ′2λ′4, so that the seventh lightbeam λ′2λ′4 is input to the light polarizing and combining element 206.

The first subelement 401, the second subelement 402, and the third lightbeam adjusting element 403 may use specific same components, or may usespecific different components. In a specific implementation process, ifnames of specific components are the same, the specific componentsshould not be considered the same.

The light polarizing and combining element 206 is configured to combinethe fifth light beam and the sixth light beam into one light beam λ1λ2λ3 λ4.

In the embodiment of the present disclosure, the light polarizing andcombining element 206 is disposed on a light path of the fifth lightbeam λ1 λ3 output by the first light filtering and combining element202, while the third light beam adjusting element 403 is disposed on alight path of the seventh light beam λ2λ′4 output by the polarizationstate changing element 204 to change the propagation direction of theseventh light beam to make the seventh light beam input to the lightpolarizing and combining element 206.

The light polarizing and combining element 206 may reflect light of somepolarization directions and transmit light of other polarizationdirections according to different light polarization directions. Anyspecific component satisfying the foregoing characteristics may be thelight polarizing and combining element 206. The light polarizing andcombining element 206 may be a polarization beam combiner (PBC).

Light beams of different wavelengths enter the light filtering andcombining element from two sides of the light filtering and combiningelement respectively, and the light filtering and combining elementtransmits light beams of some wavelengths and reflects light beams ofother wavelengths, so that the light beams transmitted or reflected bythe light filtering and combining element are located at one side of thelight filtering and combining element. By controlling angles of lightbeams of different wavelengths entering the light filtering andcombining element, the light beams transmitted or reflected by the lightfiltering and combining element may be combined into one light beam atone side of the light filtering and combining element.

Two light beams of different wavelengths may be combined into one lightbeam by using the foregoing design. Four light beams of differentwavelengths may be combined into two light beams by reusing theforegoing design.

The light emitted from the laser is polarized light, and the foregoinglight combination according to wavelengths does not change thepolarization state of each light beam, so the foregoing two light beamsstill remain their original polarization states. One light beam of thetwo light beams is adjusted by using the polarization state changingelement 204, so that the polarization states of the two light beams aredifferent.

The light beams in different polarization states enter the lightpolarizing and combining element 206 from two sides of the lightpolarizing and combining element 206, and the light polarizing andcombining element 206 transmits light beams in a polarization state andreflects light beams in other polarization states, so that the lightbeams transmitted or reflected by the light polarizing and combiningelement 206 are located at one side of the light polarizing andcombining element 206. By controlling angles of light beams in differentpolarization states entering the light polarizing and combining element206, the light beams transmitted or reflected by the light polarizingand combining element 206 may be combined into one light beam at oneside of the light polarizing and combining element 206.

Two light beams in different polarization states may be combined intoone light beam by using the foregoing design.

The first subelement 401 and the second subelement 402 make light beamsof different wavelengths locate at two sides of the light filtering andcombining element by changing the propagation directions of the lightbeams; and the third light beam adjusting element 403 make light beamsin different polarization states locate at two side of the lightpolarizing and combining element 206 by changing the propagationdirections of the light beams.

The four light beams of different wavelengths emitted from the laser arecombined into one light beam through an interaction among the firstsubelement 401, the second subelement 402, the first light filtering andcombining element 202, the second light filtering and combining element203, the polarization state changing element 204, the third light beamadjusting element 403, and the light polarizing and combining element206.

To reduce loss of light energy, a high reflection film is coated on thethird light beam adjusting element 403, so as to strengthen lightreflection.

FIG. 6 is a schematic structural diagram of another multiplexeraccording to an embodiment of the present disclosure. As shown in FIG.6, the multiplexer according to the embodiment of the present disclosureincludes a first illuminator 300 and a second illuminator 400, where afirst light beam adjusting element 201, a first light filtering andcombining element 202, and a second light filtering and combiningelement 203 are attached on a surface of the first illuminator 300, anda polarization state changing element 204, a second light beam adjustingelement 205, and a light polarizing and combining element 206 areattached on a surface of the second illuminator 400.

According to a multiplexer solution shown in any one accompany drawingof FIG. 2 to FIG. 5, a design of changing a light path thereof may beapplied to the multiplexer shown in FIG. 6, and accordingly, forms thatmay be presented in FIG. 6 all belong to the scope protected by thepresent disclosure.

For example, the multiplexer shown in FIG. 6 further includes ananti-reflection element. The anti-reflection element is attached on thesurface of the first illuminator and is configured to improvetransmission of a first light beam, a second light beam, a fifth lightbeam, and a sixth light beam.

FIG. 7 is a schematic structural diagram of another multiplexeraccording to an embodiment of the present disclosure. As shown in FIG.7, the multiplexer according to the embodiment of the present disclosureincludes a first illuminator 300 and a second illuminator 400, where afirst light beam adjusting element 201, a first light filtering andcombining element 202, a second light filtering and combining element203, and a polarization state changing element 204 are attached on asurface of the first illuminator 300, and a second light beam adjustingelement 205 and a light polarizing and combining element 206 areattached on a surface of the second illuminator 400.

In addition, the first illuminator 300 further includes ananti-reflection element 301. The anti-reflection element 301 isconfigured to improve transmission of a fifth light beam λ1 λ3.

According to a multiplexer solution shown in any one accompany drawingof FIG. 2 to FIG. 5, a design of changing a light path thereof may beapplied to the multiplexer shown in FIG. 7, and accordingly, forms thatmay be presented in FIG. 7 all belong to the scope protected by thepresent disclosure.

FIG. 8 is a schematic structural diagram of another multiplexeraccording to an embodiment of the present disclosure. As shown in FIG.8, the multiplexer according to the embodiment of the present disclosureincludes a first illuminator 300 and a second illuminator 400, where afirst light beam adjusting element 201, a first light filtering andcombining element 202, a second light filtering and combining element203, and a polarization state changing element 204 are attached on asurface of the first illuminator 300, and a second light beam adjustingelement 205 and a light polarizing and combining element 206 areattached on a surface of the second illuminator 400.

In addition, the first illuminator 300 further includes ananti-reflection element 301, and the second illuminator 400 furtherincludes an anti-reflection element 301. The anti-reflection element 301is configured to improve light transmission.

According to a multiplexer solution shown in any one accompany drawingof FIG. 2 to FIG. 5, a design of changing a light path thereof may beapplied to the multiplexer shown in FIG. 8, and accordingly, forms thatmay be presented in FIG. 8 all belong to the scope protected by thepresent disclosure.

As the multiplexer shown in any one accompany drawing of FIG. 6 to FIG.8, for example, the first illuminator may be a prism, and optical filmsof different functions are coated on each surface of the prism, so as toimplement optical functions of the first light beam adjusting element,the first light filtering and combining element, and the second lightfiltering and combining element respectively; and the second illuminatormay be a prism, and optical films of different functions are coated oneach surface of the prism, so as to implement optical functions of thepolarization state changing element, the second light beam adjustingelement, and the light polarizing and combining element.

FIG. 9 is a schematic structural diagram of another multiplexeraccording to an embodiment of the present disclosure. As shown in FIG.9, the multiplexer according to the embodiment of the present disclosurefurther includes four collimation elements. The four collimationelements are located at light paths of four light beams input to themultiplexer respectively, and each collimation element is configured toperform a collimation function on a light beam on the light path wherethe collimation element is located, which results in better directivityand more focused light energy of the collimated light beam. In anotherembodiment, the four collimation elements may be all collimation lenses.The collimation element may for example be located at any location onthe four light paths, and is preferred to be located at an input endaccessory of the multiplexer. The embodiment of the present disclosuredoes not limit the relative location relationship among the collimationelement, the first light filtering and combining element 202, and thesecond light filtering and combining element 203.

In another embodiment, the multiplexer provided in the presentdisclosure further includes an optical isolator. The optical isolator islocated at a light path of light output by the light polarizing andcombining element 206 and is configured to reduce return loss.

For example, as shown in FIG. 9, the multiplexer further includes: afirst collimation element, configured to collimate, before a first lightbeam is input to the first light beam adjusting element, the first lightbeam;

a second collimation element, configured to collimate, before a secondlight beam is input to the first light beam adjusting element, thesecond light beam;

a third collimation element, configured to collimate, before a thirdlight beam is input to the first light filtering and combining element,the third light beam; and

a fourth collimation element, configured to collimate, before a fourthlight beam is input to the second light filtering and combining element,the fourth light beam.

By collimating light, a propagation route of the light may be optimized,which ensures that the light is propagated in a straight line andfacilitates controlling a propagation angle of the light.

FIG. 10 is a structural diagram of another multiplexer according to anembodiment of the present disclosure. As shown in FIG. 10, themultiplexer according to the embodiment of the present disclosureincludes a first illuminator 501, a second illuminator 502, and a thirdilluminator 503, where a first subelement 401 and a first lightfiltering and combining element 202 are attached on a surface of thefirst illuminator 501, a second subelement 402 and a second lightfiltering and combining element 203 are attached on a surface of thesecond illuminator 502, and a polarization state changing element 204, athird light beam adjusting element 403, and a light polarizing andcombining element 206 are attached on a surface of the third illuminator503.

For example, the multiplexer shown in FIG. 10 further includes: a firstanti-reflection element, where the first anti-reflection element isattached on the surface of the first illuminator 501 and is configuredto improve transmission of a first light beam and a fifth light beam;and

a second anti-reflection element, where the second anti-reflectionelement is attached on the surface of the second illuminator 502 and isconfigured to improve transmission of a second light beam and a sixthlight beam.

FIG. 11 is a structural diagram of another multiplexer according to anembodiment of the present disclosure. As shown in FIG. 11, themultiplexer according to the embodiment of the present disclosureincludes a first illuminator 501, a second illuminator 502, and a thirdilluminator 503, where a first light beam adjusting element 201 isattached on a surface of the first illuminator 501, a first lightfiltering and combining element 202 and a second light filtering andcombining element 203 are attached on a surface of the secondilluminator 502, and a polarization state changing element 204, a secondlight beam adjusting element 205, and a light polarizing and combiningelement 206 are attached on a surface of the third illuminator 503.

For example, the multiplexer shown in FIG. 11 further includes: a firstanti-reflection element, where the first anti-reflection element isattached on the surface of the first illuminator 501 and is configuredto improve transmission of a first light beam, a second light beam, anda fifth light beam; and

a second anti-reflection element, where the second anti-reflectionelement is attached on the surface of the second illuminator 502 and isconfigured to improve transmission of a first light beam, a second lightbeam, and a sixth light beam.

In another set of embodiments, the beam combining element 202 and/203may be replaced by a beam splitting element. An additional beamabsorption element may be further include.

These embodiments are described in FIGS. 12-21 and in detail below. Thelabeling and numbering for various elements and input and output laserbeams below are refreshed from the description of FIGS. 2-11.

A multiplexer according to an embodiment of the present disclosure isconfigured to combine at least four light beams into one light beam,where the multiplexer includes a light beam adjusting element, a lightsplitting element, and a light beam combining element.

The multiplexer according to the embodiment of the present disclosuremay combine at least four light beams of different wavelengths into onelight beam. Because light emitted from a laser is polarized light, afirst light beam, a second light beam, a third light beam, and a fourthlight beam represent four polarized light beams of differentwavelengths.

The sequence of the first light beam, the second light beam, the thirdlight beam, and the fourth light beam is not fixed. The accompanydrawings merely show a sequence, and the present disclosure covers othersequences that may be implemented.

The light beam adjusting element is configured to adjust propagationdirections of the first light beam and the second light beam, so thatthe first light beam and the second light beam are input into the lightsplitting element.

The light beam adjusting element is preferred to be a total reflectionfilm, or may also be a reflection film or a prism, which is not limitedin the present disclosure. The light beam adjusting element may be anyelement that may implement adjustment of the light propagationdirection. The light propagation direction may be adjusted by usingtotal reflection of light or reflection of light, or may also beadjusted by using refraction of light. To reduce loss of light energy, ahigh reflection film may be coated on the light beam adjusting element.

The light splitting element may split light that is input into the lightsplitting element. A light splitting function of the light splittingelement may be independent or have a weak dependence on a wavelength anda polarization state of light. Wavelengths and polarization states oflight obtained after splitting and light before the splitting are thusthe same or substantially the same.

Specifically, the first light beam is split into a fifth light beam anda sixth light beam; the second light beam is split into a seventh lightbeam and an eighth light beam; the third light beam is split into aninth light beam and a tenth light beam; and the fourth light beam issplit into an eleventh light beam and a twelfth light beam.

A sub light beam obtained after the first light beam is split and a sublight beam obtained after the third light beam is split are combinedinto one output light beam in the light splitting element. A sub lightbeam obtained after the second light beam is split and a sub light beamobtained after the fourth light beam is split are combined into oneoutput light beam in the light splitting element.

Specifically, sub light beams obtained after the first light beam issplit are the fifth light beam and the sixth light beam; and sub lightbeams obtained after the third light beam is split are the ninth lightbeam and the tenth light beam. A sub light beam obtained after the firstlight beam is split and a sub light beam obtained after the third lightbeam is split are combined into one output light beam in the lightsplitting element. It may be that the fifth light beam and the ninthlight beam are combined into one output light beam; or it may be thatthe fifth light beam and the tenth light beam are combined into oneoutput light beam; or it may be that the sixth light beam and the ninthlight beam are combined into one output light beam; or it may be thatthe sixth light beam and the tenth light beam are combined into oneoutput light beam.

Sub light beams obtained after the second light beam is split are theseventh light beam and the eighth light beam; and sub light beamsobtained after the fourth light beam is split are the eleventh lightbeam and the twelfth light beam. A sub light beam obtained after thesecond light beam is split and a sub light beam obtained after thefourth light beam is split are combined into one output light beam inthe light splitting element. It may be that the seventh light beam andthe eleventh light beam are combined into one output light beam; or itmay be that the eighth light beam and the twelfth light beam arecombined into one output light beam; or it may be that the eighth lightbeam and the eleventh light beam are combined into one output lightbeam; or it may be that the eighth light beam and the twelfth light beamare combined into one output light beam.

The light splitting element splits light entering the light splittingelement, some sub light beams obtained after the split are transmittedthrough a light splitter, and some other sub light beams obtained afterthe split are reflected by the light splitting element.

When multiple light beams enter the light splitting element, each lightbeam is separately transmitted or reflected by the light splittingelement, and one combined output light beam may be obtained on a sameside of the light splitting element by controlling a location and anangle of each light beam entering the light splitting element.

The light beam combining element is configured to combine the outputlight beams of the light splitting element into one light beam.

A sub light beam of the first light beam and a sub light beam of thethird light beam are combined into one output light beam by using thelight splitting element, and a sub light beam of the second light beamand a sub light beam of the fourth light beam are combined into oneoutput light beam by using the light splitting element, so that thelight splitting element outputs at least two output light beams. Thelight beam combining element combines the output light beams of thelight splitting element into one light beam.

The first light beam, the second light beam, the third light beam, andthe fourth light beam are split by the light splitting element. In thelight splitting element, a sub light beam obtained after the first lightbeam is split and a sub light beam obtained after the third light beamis split are combined into one output light beam, and a sub light beamobtained after the second light beam is split and a sub light beamobtained after the fourth light beam is split are combined into oneoutput light beam, so as to implement combining the four light beamsinto two light beams. The light beam combining element combines the twolight beams output by the light splitting element into one light beam.Finally, the four light beams are combined into one light beam.

The multiplexer provided in the present disclosure is configured toreceive at least four light beams of different wavelengths emitted froma laser, the light beam adjusting element is configured to adjustpropagation directions of a first light beam and a second light beam, sothat the first light beam and the second light beam are input into thelight splitting element; the light splitting element is configured to:separately split the first light beam, the second light beam, a thirdlight beam, and a fourth light beam, combine sub light beams obtainedafter the first light beam is split and sub light beams obtained afterthe third light beam is split into one output light beam, and combinesub light beams obtained after the second light beam is split and sublight beams obtained after the fourth light beam is split into oneoutput light beam; and the light beam combining element is configured tocombine the output light beams of the light splitting element into onelight beam, thereby implementing combining the at least four light beamsinto one light beam.

During a process of combining at least four light beams into one lightbeam, a light beam is reflected four times at the light beam adjustingelement, the light splitting element, and the light beam combiningelement; and a light beam is reflected at least zero time. When thecombing at least four light beams into one light beam is implemented,the four light beams are reflected at most six times, and compared withthe conventional art, not only the maximum number of reflection times ofa light beam is reduced but also the total number of reflection times ofthe light beams is reduced, and therefore, the number of reflectiontimes of light during the light combination process is reduced.

FIG. 12 is a schematic structural diagram of a multiplexer according toan embodiment of the present disclosure. As shown in FIG. 12, themultiplexer according to the embodiment of the present disclosure isconfigured to combine at least four light beams into one light beam,where the multiplexer includes a light beam adjusting element 201, alight splitting element 202, and a light beam combining element, and thelight beam combining element includes a polarization state adjustingelement 204, a light reflection element 205, and a polarization beamcombining element (also referred to as polarization beam combiner, lightpolarization and combining element) 206.

The sequence of a first light beam λ1, a second light beam λ2, a thirdlight beam λ3, and a fourth light beam λ4 is not fixed. FIG. 12 merelyshows a sequence, and the present disclosure covers other sequences thatmay be implemented.

The first light beam λ1 and the second light beam λ2 are separatelypropagated onto the light beam adjusting element 201 and are reflectedby the light beam adjusting element 201. The third light beam λ3 and thefourth light beam λ4 are separately propagated onto the light splittingelement 202. λ1 not only refers to the first light beam λ1 but alsorefers to a wavelength of the first light beam λ1. Similarly, λ2 notonly refers to the second light beam λ2 but also refers to a wavelengthof the second light beam λ2; λ3 not only refers to the third light beamλ3 but also refers to a wavelength of the third light beam λ3; and λ4not only refers to the fourth light beam λ4 but also refers to awavelength of the fourth light beam λ4.

The light beam adjusting element 201 is configured to adjust propagationdirections of the first light beam λ1 and the second light beam λ2, sothat the first light beam λ1 and the second light beam λ2 are input intothe light splitting element 202.

The first light beam λ1 is split into a fifth light beam and a sixthlight beam, and wavelengths of the fifth light beam and the sixth lightbeam are the same as the wavelength λ1 of the first light beam; thesecond light beam λ2 is split into a seventh light beam and an eighthlight beam, and wavelengths of the seventh light beam and the eighthlight beam are the same as the wavelength λ2 of the second light beam;the third light beam λ3 is split into a ninth light beam and a tenthlight beam, and wavelengths of the ninth light beam and the tenth lightbeam are the same as the wavelength λ3 of the third light beam; and thefourth light beam λ4 is split into an eleventh light beam and a twelfthlight beam, and wavelengths of the eleventh light beam and the twelfthlight beam are the same as the wavelength λ4 of the fourth light beam.

A sub light beam obtained after the first light beam λ1 is split and asub light beam obtained after the third light beam λ3 is split arecombined into one output light beam in the light splitting element. Asub light beam obtained after the second light beam λ2 is split and asub light beam obtained after the fourth light beam λ4 is split arecombined into one output light beam in the light splitting element.

Specifically, sub light beams obtained after the first light beam λ1 issplit are the fifth light beam and the sixth light beam; and sub lightbeams obtained after the third light beam λ3 is split are the ninthlight beam and the tenth light beam. A sub light beam obtained after thefirst light beam λ1 is split and a sub light beam obtained after thethird light beam λ3 is split are combined into one output light beam inthe light splitting element, and a wavelength of the output light beamis λ1λ3.

It may be that the fifth light beam and the ninth light beam arecombined into one output light beam; or it may be that the fifth lightbeam and the tenth light beam are combined into one output light beam;or it may be that the sixth light beam and the ninth light beam arecombined into one output light beam; or it may be that the sixth lightbeam and the tenth light beam are combined into one output light beam.Specifically, after the first light beam and the third light beam aresplit and combined by using the light splitting element, a light beamλ1λ3 a that is input into a beam combiner is formed; and sub light beamsobtained after the second light beam λ2 is split are the seventh lightbeam and the eighth light beam; and sub light beams obtained after thefourth light beam λ4 is split are the eleventh light beam and thetwelfth light beam; and a sub light beam obtained after the first lightbeam λ2 is split and a sub light beam obtained after the third lightbeam λ4 is split are combined into one output light beam in the lightsplitting element, and a wavelength of the output light beam is λ2λ4.

It may be that the seventh light beam and the eleventh light beam arecombined into one output light beam; or it may be that the eighth lightbeam and the twelfth light beam are combined into one output light beam;or it may be that the eighth light beam and the eleventh light beam arecombined into one output light beam; or it may be that the eighth lightbeam and the twelfth light beam are combined into one output light beam.Specifically, after the second light beam and the fourth light beam aresplit and combined by using the light splitting element, a light beamλ2λ4 a that is input into a beam combiner is formed.

The light splitting element splits light entering the light splittingelement, some sub light beams obtained after the split are transmittedthrough a light splitter, and some other sub light beams obtained afterthe split are reflected by the light splitting element.

When multiple light beams enter the light splitting element, each lightbeam is separately transmitted or reflected by the light splittingelement, and one combined output light beam may be obtained on a sameside of the light splitting element by controlling a location and anangle of each light beam entering the light splitting element.

Specifically, the first light beam and the third light beam are combinedinto the output light beam λ1λ3 a on one side of the light splittingelement, and are combined into an output light beam λ1λ3 b on the otherside of the light splitting element. The second light beam and thefourth light beam are combined into the output light beam λ2λ4 a on oneside of the light splitting element, and are combined into an outputlight beam λ2λ4 b on another side of the light splitting element.

The light beam combining element is configured to combine the outputlight beams of the light splitting element into one light beam.

Specifically, the light beam combining element includes the polarizationstate adjusting element 204, the light reflection element 205, and apolarization beam combing element 206.

The output light beam λ1λ3 a of the light splitting element 202 is inputto the light reflection element 205, and is input to the lightpolarizing and combing element 206 upon reflection of the lightreflection element 205. The output light beam λ2λ4 a of the lightsplitting element 202 is input to the polarization state adjustingelement 204 to obtain a light beam λ2λ4 a that is input into the lightpolarizing and combing element 206, and the light beam λ1λ3 a and thelight beam λ2λ4 a are combined into a light beam λ1λ2λ3λ4 in the lightpolarizing and combing element. The light beam λ′2λ′4 a and the lightbeam λ2λ4 a have the same wavelength and different polarization states.

A sub light beam of the first light beam λ1 and a sub light beam of thethird light beam λ3 are combined into one output light beam by using thelight splitting element, and a sub light beam of the second light beamλ2 and a sub light beam of the fourth light beam λ4 are combined intoone output light beam by using the light splitting element, so that thelight splitting element outputs at least two output light beams. Thelight beam combining element combines the output light beams of thelight splitting element into one light beam.

In addition, the multiplexer further includes a light absorbing element203. After the first light beam and the third light beam are split andcombined by using the light splitting element, the light beam λ1λ3 bthat is input into the light absorbing element 203 is formed; and afterthe second light beam and the fourth light beam are split and combinedby using the light splitting element, the light beam λ2λ4 b that isinput into the light absorbing element 203 is formed.

FIG. 13 is a schematic structural diagram of another multiplexeraccording to an embodiment of the present disclosure. As shown in FIG.13, the multiplexer according to the embodiment of the presentdisclosure is configured to combine at least four light beams into onelight beam, where the multiplexer includes a light beam adjustingelement 201, a light splitting element 202, and a light beam combiningelement, and the light beam combining element includes a polarizationstate adjusting element 204, a light reflection element 205, and apolarization beam combining element 206.

A first light beam λ1 and a second light beam λ2 are separatelypropagated onto the light beam adjusting element 201 and are reflectedby the light beam adjusting element 201. A third light beam λ3 and afourth light beam λ4 are separately propagated onto the light splittingelement 202. The light beam adjusting element 201 is configured toadjust propagation directions of the first light beam λ1 and the secondlight beam λ2, so that the first light beam λ1 and the second light beamλ2 are input into the light splitting element 202.

The first light beam λ1 is split into a fifth light beam and a sixthlight beam, and wavelengths of the fifth light beam and the sixth lightbeam are the same as a wavelength λ1 of the first light beam; the secondlight beam λ2 is split into a seventh light beam and an eighth lightbeam, and wavelengths of the seventh light beam and the eighth lightbeam are the same as a wavelength λ2 of the second light beam; the thirdlight beam λ3 is split into a ninth light beam and an tenth light beam,and wavelengths of the ninth light beam and the tenth light beam are thesame as a wavelength λ3 of the third light beam; and the fourth lightbeam λ4 is split into an eleventh light beam and a twelfth light beam,and wavelengths of the eleventh light beam and the twelfth light beamare the same as a wavelength λ4 of the fourth light beam.

A sub light beam obtained after the first light beam λ1 is split and asub light beam obtained after the third light beam λ3 is split arecombined into one output light beam in the light splitting element. Asub light beam obtained after the second light beam λ2 is split and asub light beam obtained after the fourth light beam λ4 is split arecombined into one output light beam in the light splitting element.

Specifically, sub light beams obtained after the first light beam λ1 issplit are the fifth light beam and the sixth light beam; and sub lightbeams obtained after the third light beam λ3 is split are the ninthlight beam and the tenth light beam. A sub light beam obtained after thefirst light beam λ1 is split and a sub light beam obtained after thethird light beam λ3 is split are combined into one output light beam inthe light splitting element, and a wavelength of the output light beamis λ1λ3; and after the first light beam and the third light beam aresplit and combined by using the light splitting element, a light beamλ1λ3 a that is input into a beam combiner is formed; and a sub lightbeam obtained after the first light beam λ2 is split and a sub lightbeam obtained after the third light beam λ4 is split are combined intoone output light beam in the light splitting element, and a wavelengthof the output light beam is λ2λ4; and after the second light beam andthe fourth light beam are split and combined by using the lightsplitting element, a light beam λ2λ4 a that is input into a beamcombiner is formed.

The first light beam and the third light beam are combined into theoutput light beam λ1λ3 a on one side of the light splitting element, andare combined into an output light beam λ1λ3 b on the other side of thelight splitting element. The second light beam and the fourth light beamare combined into the output light beam λ2λ4 a on one side of the lightsplitting element, and are combined into an output light beam λ2λ4 b onanother side of the light splitting element.

The light beam combining element is configured to combine the outputlight beams of the light splitting element into one light beam.

Specifically, the light beam combining element includes the polarizationstate adjusting element 204, the light reflection element 205, and alight polarizing and combing element 206.

The output light beam λ1λ3 a of the light splitting element 202 is inputto the light polarizing and combing element 206. The output light beamλ2λ4 a of the light splitting element 202 is input to the polarizationstate adjusting element 204 to obtain a light beam λ2λ4 a that is inputinto the light polarizing and combing element 206. The light beam λ2λ4 ais input to the light reflection element 205, and is input to the lightpolarizing and combing element 206 upon reflection of the lightreflection element. The light beam λ1λ3 a and the light beam λ2λ4 a arecombined into a light beam λ1λ2λ3λ4 in the polarization beam combiningelement. The light beam λ2λ4 a and the light beam λ2λ4 a have the samewavelength and different polarization states.

A sub light beam of the first light beam λ1 and a sub light beam of thethird light beam λ3 are combined into one output light beam by using thelight splitting element, and a sub light beam of the second light beamλ2 and a sub light beam of the fourth light beam λ4 are combined intoone output light beam by using the light splitting element, so that thelight splitting element outputs at least two output light beams. Thelight beam combining element combines the output light beams of thelight splitting element into one light beam.

In addition, the multiplexer further includes a light absorbing element203. After the first light beam and the third light beam are split andcombined by using the light splitting element, the light beam λ1λ3 bthat is input into the light absorbing element 203 is formed; and afterthe second light beam and the fourth light beam are split and combinedby using the light splitting element, the light beam λ2λ4 b that isinput into the light absorbing element 203 is formed.

FIG. 14 is a schematic structural diagram of another multiplexeraccording to an embodiment of the present disclosure.

As shown in FIG. 14, a light beam adjusting element includes a firstsubelement 301 and a second subelement 302. The first subelement 301 isconfigured to adjust a propagation direction of a first light beam. Thesecond subelement 302 is configured to adjust a propagation direction ofa second light beam.

As shown in FIG. 14, a light splitting element includes a thirdsubelement 303 and a fourth subelement 304. The third subelement 303 isconfigured to split the first light beam and a third light beam. Thefourth subelement 304 is configured to split the second light beam and afourth light beam.

As shown in FIGS. 16 and 17, a multiplexer according to an embodiment ofthe present disclosure includes a first illuminator 400 and a secondilluminator 403. A light beam adjusting element 201 and a light splitter202 are attached on a surface of the first illuminator. A polarizationstate adjusting element 204, a light reflection element 205, and apolarization beam combining element 206 are attached on a surface of thesecond illuminator.

As shown in FIG. 15, a multiplexer according to an embodiment of thepresent disclosure includes a first illuminator 401, a secondilluminator 402, and a third illuminator 403. A first subelement and athird subelement are attached on a surface of the first illuminator 401.A second subelement and a fourth subelement are attached on a surface ofthe second illuminator 402. A polarization state changing element, alight reflection element, and a light polarizing and combing element areattached on a surface of the third illuminator 403.

FIG. 18 is a schematic structural diagram of another multiplexeraccording to an embodiment of the present disclosure. As shown in FIG.18, the multiplexer according to the embodiment of the presentdisclosure is configured to combine at least four light beams into onelight beam, where the multiplexer includes a light beam adjustingelement 201, a light splitting element 202, and a light beam combiningelement, and the light beam combining element includes a lightreflection element 205 and a light filtering and combining element 207.

The sequence of a first light beam λ1, a second light beam λ2, a thirdlight beam λ3, and a fourth light beam λ4 is not fixed. FIG. 18 merelyshows a sequence, and the present disclosure covers other sequences thatmay be implemented.

The first light beam λ1 and the second light beam λ2 are separatelypropagated onto the light beam adjusting element 201 and are reflectedby the light beam adjusting element 201. The third light beam λ3 and thefourth light beam λ4 are separately propagated onto the light splittingelement 202. λ1 not only refers to the first light beam λ1 but alsorefers to a wavelength of the first light beam λ1. Similarly, λ2 notonly refers to the second light beam λ2 but also refers to a wavelengthof the second light beam λ2; λ3 not only refers to the third light beamλ3 but also refers to a wavelength of the third light beam λ3; and λ4not only refers to the fourth light beam λ4 but also refers to awavelength of the fourth light beam λ4.

The light beam adjusting element 201 is configured to adjust propagationdirections of the first light beam λ1 and the second light beam λ2, sothat the first light beam λ1 and the second light beam λ2 are input intothe light splitting element 202.

The first light beam λ1 is split into a fifth light beam and a sixthlight beam, and wavelengths of the fifth light beam and the sixth lightbeam are the same as the wavelength λ1 of the first light beam; thesecond light beam λ2 is split into a seventh light beam and an eighthlight beam, and wavelengths of the seventh light beam and the eighthlight beam are the same as the wavelength λ2 of the second light beam;the third light beam λ3 is split into a ninth light beam and an tenthlight beam, and wavelengths of the ninth light beam and the tenth lightbeam are the same as the wavelength λ3 of the third light beam; and thefourth light beam λ4 is split into an eleventh light beam and a twelfthlight beam, and wavelengths of the eleventh light beam and the twelfthlight beam are the same as the wavelength λ4 of the fourth light beam.

A sub light beam obtained after the first light beam λ1 is split and asub light beam obtained after the third light beam λ3 is split arecombined into one output light beam in the light splitting element. Asub light beam obtained after the second light beam λ2 is split and asub light beam obtained after the fourth light beam λ4 is split arecombined into one output light beam in the light splitting element.

Specifically, sub light beams obtained after the first light beam λ1 issplit are the fifth light beam and the sixth light beam; and sub lightbeams obtained after the third light beam λ3 is split are the ninthlight beam and the tenth light beam. A sub light beam obtained after thefirst light beam λ1 is split and a sub light beam obtained after thethird light beam λ3 is split are combined into one output light beam inthe light splitting element, and a wavelength of the output light beamis λ1λ3.

It may be that the fifth light beam and the ninth light beam arecombined into one output light beam; or it may be that the fifth lightbeam and the tenth light beam are combined into one output light beam;or it may be that the sixth light beam and the ninth light beam arecombined into one output light beam; or it may be that the sixth lightbeam and the tenth light beam are combined into one output light beam.Specifically, after the first light beam and the third light beam aresplit and combined by using the light splitting element, a light beamλ1λ3 a that is input into a beam combiner is formed; and sub light beamsobtained after the second light beam λ2 is split are the seventh lightbeam and the eighth light beam; and sub light beams obtained after thefourth light beam λ4 is split are the eleventh light beam and thetwelfth light beam; and a sub light beam obtained after the first lightbeam λ2 is split and a sub light beam obtained after the third lightbeam λ4 is split are combined into one output light beam in the lightsplitting element, and a wavelength of the output light beam is λ2λ4.

It may be that the seventh light beam and the eleventh light beam arecombined into one output light beam; or it may be that the eighth lightbeam and the twelfth light beam are combined into one output light beam;or it may be that the eighth light beam and the eleventh light beam arecombined into one output light beam; or it may be that the eighth lightbeam and the twelfth light beam are combined into one output light beam.Specifically, after the second light beam and the fourth light beam aresplit and combined by using the light splitting element, a light beamλ2λ4 a that is input into a beam combiner is formed.

The light splitting element splits light entering the light splittingelement, some sub light beams obtained after the split are transmittedthrough a light splitter, and some other sub light beams obtained afterthe split are reflected by the light splitting element.

When multiple light beams enter the light splitting element, each lightbeam is separately transmitted or reflected by the light splittingelement, and one combined output light beam may be obtained on a sameside of the light splitting element by controlling a location and anangle of each light beam entering the light splitting element.

Specifically, the first light beam and the third light beam are combinedinto the output light beam λ1λ3 a on one side of the light splittingelement, and are combined into an output light beam λ1λ3 b on the otherside of the light splitting element. The second light beam and thefourth light beam are combined into the output light beam λ2λ4 a on oneside of the light splitting element, and are combined into an outputlight beam λ2λ4 b on another side of the light splitting element.

The light beam combining element is configured to combine the outputlight beams of the light splitting element into one light beam.

Specifically, the light beam combining element includes a lightreflection element 205 and a light filtering and combining element 207.

The output light beam λ2λ4 a of the light splitting element 202 is inputinto the light reflection element 205, and is input into the lightfiltering and combining element 207 upon reflection of the lightreflection element 205. The output light beam λ1λ3 a of the lightsplitting element 202 is input into the light filtering and combiningelement 207, and the light filtering and combining element 207 combinesthe light beam λ1λ3 a and the light beam λ2λ4 a into a light beamλ1λ2λ3λ4.

A sub light beam of the first light beam λ1 and a sub light beam of thethird light beam λ3 are combined into one output light beam by using thelight splitting element, and a sub light beam of the second light beamλ2 and a sub light beam of the fourth light beam λ4 are combined intoone output light beam by using the light splitting element, so that thelight splitting element outputs at least two output light beams. Thelight beam combining element combines the output light beams of thelight splitting element into one light beam.

In addition, the multiplexer further includes a light absorbing element203. After the first light beam and the third light beam are split andcombined by using the light splitting element, the light beam λ1λ3 bthat is input into the light absorbing element 203 is formed; and afterthe second light beam and the fourth light beam are split and combinedby using the light splitting element, the light beam λ2λ4 b that isinput into the light absorbing element 203 is formed.

As shown in FIG. 19, a light beam adjusting element includes a firstsubelement 301 and a second subelement 302. The first subelement 301 isconfigured to adjust a propagation direction of a first light beam. Thesecond subelement 302 is configured to adjust a propagation direction ofa second light beam.

As shown in FIG. 19, a light splitting element includes a thirdsubelement 303 and a fourth subelement 304. The third subelement 303 isconfigured to split the first light beam and a third light beam. Thefourth subelement 304 is configured to split the second light beam and afourth light beam.

As shown in FIG. 20, a multiplexer according to an embodiment of thepresent disclosure includes a first illuminator 400 and a secondilluminator 403. A light beam adjusting element 201 and a light splitter202 are attached on a surface of the first illuminator. A lightreflection element 205 and a light filtering and combining element 207are attached on a surface of the second illuminator.

As shown in FIG. 21, a multiplexer according to an embodiment of thepresent disclosure includes a first illuminator 401, a secondilluminator 402, and a third illuminator 404. A first subelement and athird subelement are attached on a surface of the first illuminator 401.A second subelement and a fourth subelement are attached on a surface ofthe second illuminator 402. A light reflection element and a lightfiltering and combining element are attached or coated on a surface ofthe third illuminator 404.

Finally, it should be noted that the foregoing embodiments are merelyintended for describing the technical solutions of the presentdisclosure rather than limiting the present disclosure. Although thepresent disclosure is described in detail with reference to theforegoing embodiments, persons of ordinary skill in the art shouldunderstand that they may still make modifications to the technicalsolutions described in the foregoing embodiments or make equivalentreplacements to some technical features thereof, as long as suchmodifications or replacements do not cause the essence of correspondingtechnical solutions to depart from the spirit and scope of the technicalsolutions of the embodiments of the present disclosure.

What is claimed is:
 1. A multiplexer for combining light beams ofdifferent wavelengths into one light beam, comprising: a first lightbeam adjusting element configured to adjust propagation directions of afirst light beam and a second light beam; a first light splittingelement configured to split each of the first light beam and a thirdlight beam into two split portions; combine one of the two splitportions of the third light beam and one of the two split portions ofthe first light beam adjusted by the first light beam adjusting elementinto a fifth light beam; split each of the second light beam and afourth light beam into two split portions; and combine one of the twosplit portions of the fourth light beam and one of the two splitportions of the second light beam adjusted by the first light beamadjusting element into a sixth light beam; and a light combining elementconfigured to combine the fifth light beam and sixth light beam into asingle light beam.
 2. The multiplexer of claim 1, wherein: one of thetwo split portions of the first, second, third, or fourth beams is atransmission through the first light splitting element; and the other ofthe two split portions of the first, second, third, or fourth beams is areflection off the first light splitting element.
 3. The multiplexer ofclaim 1, wherein the first light splitting element comprises a firstlight splitting subelement and a second light splitting subelement,wherein: the first light splitting subelement is configured to split andcombine the first light beam and the third light beam; and the secondlight splitting subelement is configured to split and combine the secondlight beam and the fourth light beam.
 4. The multiplexer of claim 1,wherein the light combining element comprises: a second light adjustingelement configured to adjust a propagation direction of the fifth orsixth light beam; and a light combining subelement configured to combinethe fifth and sixth light beams after the adjustment of the propagationdirection of the fifth or sixth light beams into the single light beam.5. The multiplexer of claim 4, wherein the light combining subelementcomprises a dichroic light combiner configured to combine light beams ofdifferent wavelengths.
 6. The multiplexer of claim 1, wherein the lightcombining element comprises a polarization beam combiner.
 7. Themultiplexer of claim 6, further comprising a polarization state changingelement disposed in the fifth or the sixth light beam between the firstlight splitting element and the light combining element and isconfigured to modify the polarization state of the fifth or the sixthlight beam such that the fifth light beam and the sixth light beam areof orthogonal polarizations.
 8. The multiplexer of claim 1, furthercomprising a light absorption element configured to absorb the otherportion of the two split portions of each of the first, second, third,and fourth light beams.
 9. The multiplexer of claim 1, furthercomprising a first illuminator comprising the first light beam adjustingelement and the first light splitting element attached on a surface ofthe first illuminator.
 10. The multiplexer according to claim 9, whereinthe first illuminator further comprises an anti-reflection coating on aportion of the first illuminator to increase transmission of the firstlight beam, the second light beam, the fifth light beam, or the sixthlight beam.
 11. The multiplexer according to claim 9, further comprisinga polarization state changing element attached to the surface of thefirst illuminator and configured to adjust polarization state of one ofthe fifth and the sixth light beam.
 12. The multiplexer of claim 9,further comprising a second illuminator comprising the light combiningelement attached on a surface of the second illuminator.
 13. Themultiplexer according to claim 12, wherein the light combining elementcomprises: a second light adjusting element configured to adjust thepropagation direction of the fifth or sixth light beam; and a lightcombining subelement configured to combine the fifth and sixth lightbeams after the adjustment of a propagation direction of the fifth orsixth light beams into the single light beam, and wherein the secondlight adjusting element and the light combining subelement is attachedon the surface of the second illuminator.
 14. The multiplexer accordingto claim 12, further comprising a polarization state changing elementattached to the surface of the second illuminator and configured toadjust polarization state of one of the fifth or the sixth light beam.15. The multiplexer according to claim 12, wherein the secondilluminator further comprises an anti-reflection coating on a portion ofthe second illuminator to increase transmission of the fifth light beam,the sixth light beam, or the combined single light beam.
 16. Themultiplexer according to claim 1, further comprising: a firstilluminator, wherein the first light beam adjusting element is attachedon a surface of the first illuminator; and a second illuminator, whereinthe first light splitting element is attached on a surface of the secondilluminator.
 17. The multiplexer according to claim 16, furthercomprising: a first anti-reflection coating on a portion of the firstilluminator to increase transmission of at least the first light beamand the second light beam; and a second anti-reflection coating on aportion of the second illuminator to increase transmission of at leastthe second light beam and the first light beam.
 18. The multiplexeraccording to claim 16, further comprising a third illuminator, whereinthe light combining element is attached on a surface of the thirdilluminator.
 19. The multiplexer of claim 1, wherein the first lightadjusting element comprises a first light adjusting subelement and asecond light adjusting subelement, wherein the first light adjustingsubelement is configured to adjust propagation direction of the firstlight beam and the second light adjusting subelement is configured toadjust propagation direction of the second light beam.
 20. Themultiplexer of claim 19, wherein the first light splitting elementcomprises a first light splitting subelement and a second lightsplitting subelement, wherein the first light splitting subelement isconfigured to split and combine the first light beam and the third lightbeam; and the second light splitting subelement is configured to splitand combine the second light beam and the fourth light beam.
 21. Themultiplexer according to claim 20, further comprising a firstilluminator, wherein the first light adjusting subelement and the firstlight splitting subelement or the second light adjusting subelement andthe second light splitting subelement are attached on a surface of thefirst illuminator.
 22. The multiplexer according to claim 20, furthercomprising a second illuminator, wherein the light combining element isattached on a surface of the second illuminator.
 23. The multiplexeraccording to claim 1, further comprising: a first collimation element,configured to collimate, before the first light beam is input to thefirst light beam adjusting element, the first light beam; a secondcollimation element, configured to collimate, before the second lightbeam is input to the first light beam adjusting element, the secondlight beam; a third collimation element, configured to collimate, beforethe third light beam is input to the first light splitting element, thethird light beam; and a fourth collimation element, configured tocollimate, before the fourth light beam is input to the first lightsplitting element, the fourth light beam.
 24. The multiplexer accordingto claim 1, further comprising: an optical isolator located after thelight combining element and on a light path of the single light beamcombined by the light combining element.